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 ###Instrução: Qual é a média do índice superior MJ/Nm 3 para a entrada do índice superior Kcal/Nm 3 de 19.376?
 ###Tabelas: CREATE TABLE wobbe_index_of_common_fuel_gases (wobbe_index_of_common_fuel_gases_id AUTO_INCREMENT PRIMARY KEY, Fuel gas VARCHAR, Upper index Kcal/ Nm 3 INT, Lower index Kcal/ Nm 3 INT, Upper index MJ/ Nm 3 INT, Lower index MJ/ Nm 3 INT) CREATE TABLE spaceports_with_achieved_vertical_launches_of_humans (spaceports_with_achieved_vertical_launches_of_humans_id AUTO_INCREMENT PRIMARY KEY, Spaceport VARCHAR, Launch complex VARCHAR, Launcher VARCHAR, Spacecraft VARCHAR, Flights VARCHAR, Years VARCHAR) CREATE TABLE pool_3 (pool_3_id AUTO_INCREMENT PRIMARY KEY, Team VARCHAR, Tries for INT, Tries against INT, Try diff VARCHAR, Points for INT, Points against INT, Points diff VARCHAR) CREATE TABLE non-championship_race_results (non-championship_race_results_id AUTO_INCREMENT PRIMARY KEY, Race Name VARCHAR, Circuit VARCHAR, Date VARCHAR, Winning driver VARCHAR, Constructor VARCHAR, Report VARCHAR) CREATE TABLE 4-8-4 (4-8-4_id AUTO_INCREMENT PRIMARY KEY, Class VARCHAR, Wheel arrangement VARCHAR, Fleet number(s) VARCHAR, Manufacturer VARCHAR, Serial numbers VARCHAR, Year made VARCHAR, Quantity made VARCHAR, Quantity preserved VARCHAR, Year(s) retired VARCHAR)  
SELECT AVG Upper index MJ/ Nm 3 FROM wobbe_index_of_common_fuel_gases WHERE Upper index Kcal/ Nm 3 = 19,376